"The demo didn't go into much detail about new weapons, although it did suggest weapons may often be in short supply, as considerable use was made of the Gravity Gun. However, we did see one new weapon, the Strider Buster: a sort of magnetic mine which you can attach to Striders' backs, and then explode by shooting it."

"And puzzles get a lot trickier as the game progresses. Unlike the dark, fleshy corridors in Prey, Portal's clean, white environments have been presented with a simple, easy-on-the-eyes attitude, providing Valve with a little more freedom to concoct wild and head-spinning tasks. Once I'd got my hands on the all-important portal gun, extra set-pieces and apparatus were added to the mix, such as moving platforms, bouncing energy balls and rotating sentry guns. But what impressed me the most was the subtle efforts Valve has made to keep everything obvious - visual cues like shadows and lights on the ceiling, so you know exactly where to place your space-bending hole."